Expandable Fusion Device and Method of Installation Thereof

ABSTRACT

The present invention provides an expandable fusion device capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. In one embodiment, the fusion device includes a body portion, a first endplate, and a second endplate, the first and second endplates capable of being moved in a direction away from the body portion into an expanded configuration or capable of being moved towards the body portion into an unexpanded configuration. The fusion device is capable of being deployed and installed in both configurations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/823,736 filed on Jun. 25, 2010, which is incorporated in its entiretyherein.

FIELD OF THE INVENTION

The present invention relates to the apparatus and method for promotingan intervertebral fusion, and more particularly relates to an expandablefusion device capable of being inserted between adjacent vertebrae tofacilitate the fusion process.

BACKGROUND OF THE INVENTION

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, present methods forinstalling a conventional fusion device often require that the adjacentvertebral bodies be distracted to restore a diseased disc space to itsnormal or healthy height prior to implantation of the fusion device. Inorder to maintain this height once the fusion device is inserted, thefusion device is usually dimensioned larger in height than the initialdistraction height. This difference in height can make it difficult fora surgeon to install the fusion device in the distracted intervertebralspace.

As such, there exists a need for a fusion device capable of beinginstalled inside an intervertebral disc space at a minimum to nodistraction height and for a fusion device that can maintain a normaldistance between adjacent vertebral bodies when implanted.

SUMMARY OF THE INVENTION

In an exemplary embodiment, the present invention provides an expandablefusion device capable of being installed inside an intervertebral discspace to maintain normal disc spacing and restore spinal stability,thereby facilitating an intervertebral fusion. In one embodiment, thefusion device includes a body portion, a first endplate, and a secondendplate. The first and second endplates are capable of being moved in adirection away from the body portion into an expanded configuration orcapable of being moved towards the body portion into an unexpandedconfiguration. The expandable fusion device is capable of being deployedand installed in the unexpanded configuration or the expandedconfiguration.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred or exemplary embodiments of the invention, areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present invention;

FIG. 2 is an exploded view of the expandable fusion device of FIG. 1;

FIG. 3 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position;

FIG. 4 is a side cross-sectional view of the expandable fusion device ofFIG. 1 shown with one of the endplates removed;

FIG. 5 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 1 shown in an unexpanded position;

FIG. 6 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 1 shown in an expanded position;

FIG. 7 is a side schematic view of the expandable fusion device of FIG.1 having different endplates;

FIG. 8 is a partial side schematic view of the expandable fusion deviceof FIG. 1 showing different modes of endplate expansion;

FIG. 9 is a side schematic view of the expandable fusion device of FIG.1 with artificial endplates shown between adjacent vertebrae;

FIG. 10 is a side view cross-sectional view of another embodiment of anexpandable fusion device shown in an unexpanded position;

FIG. 11 is a side view cross-sectional view of the expandable fusiondevice of FIG. 10 shown in an expanded position;

FIG. 12 is a side view of the expandable fusion device of FIG. 10showing the translation member and the ramped insert;

FIG. 13 is a front perspective view of the expandable fusion device ofFIG. 10 showing the translation member and the ramped insert;

FIG. 14 is a rear perspective of another embodiment of an expandablefusion device with the endplates having a threaded hole;

FIG. 15 is a top view of another embodiment of an expandable fusiondevice shown in an unexpanded position;

FIG. 16 is a bottom view of the expandable fusion device of FIG. 15;

FIG. 17 is top view of the expandable fusion device of FIG. 15 shown inan expanded position;

FIG. 18 is an exploded perspective view of another embodiment of anexpandable fusion device;

FIG. 19 is an end view of the expandable fusion device of FIG. 18 in anunexpanded position;

FIG. 20 is an end view of the expandable fusion device of FIG. 18 in anexpanded position;

FIG. 21 is a perspective view of another embodiment of an expandablefusion device;

FIG. 22 is a top view of the expandable fusion device of FIG. 21;

FIG. 23 is a perspective view of the expandable fusion device of FIG. 21with a closed end.

FIG. 24 is a front view of the expandable fusion device of FIG. 23 shownbetween adjacent vertebrae in an unexpanded position; and

FIG. 25 is a front view of the expandable fusion device of FIG. 23 shownbetween adjacent vertebrae in an expanded position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disk material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an exemplary embodiment of an expandable fusiondevice 10 is shown between adjacent vertebral bodies 2 and 3. The fusiondevice 10 engages the endplates 4 and 5 of the adjacent vertebral bodies2 and 3 and, in the installed position, maintains normal intervertebraldisc spacing and restores spinal stability, thereby facilitating anintervertebral fusion. The expandable fusion device 10 can bemanufactured from a number of materials including titanium, stainlesssteel, titanium alloys, non-titanium metallic alloys, polymericmaterials, plastics, plastic composites, PEEK, ceramic, and elasticmaterials.

In an exemplary embodiment, bone graft or similar bone growth inducingmaterial can be introduced around and within the fusion device 10 tofurther promote and facilitate the intervertebral fusion. The fusiondevice 10, in one embodiment, is preferably packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the fusion device. Such bone graft may be packedbetween the endplates of the adjacent vertebral bodies prior to,subsequent to, or during implantation of the fusion device.

With reference to FIG. 2, an exploded perspective view of one embodimentof the fusion device 10 is shown. In an exemplary embodiment, the fusiondevice 10 includes a body portion 12, a first endplate 14, a secondendplate 16, a translation member 18, an actuation member 20, and aninsert 22.

With additional reference to FIGS. 3-6, in an exemplary embodiment, thebody portion 12 has a first end 24, a second end 26, a first sideportion 28 connecting the first end 24 and the second end 26, and asecond side portion 29 on the opposing side of the body portion 12connecting the first end 24 and the second end 26. The body portion 12further includes an upper end 30, which is sized to receive at least aportion of the first endplate 14, and a lower end 32, which is sized toreceive at least a portion of the second endplate 16.

The first end 24 of the body portion 12, in an exemplary embodiment,includes at least one angled surface 34, but can include multiple angledsurfaces. The angled surface 34 can serve to distract the adjacentvertebral bodies when the fusion device 10 is inserted into anintervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 10 is inserted into an intervertebralspace.

The second end 26 of the body portion 12, in an exemplary embodiment,includes an opening 36 which may include threading. In another exemplaryembodiment, the opening 36 may include ratchet teeth instead ofthreading. The opening 36 extends from the second end 26 of the bodyportion 12 into a central opening (not illustrated) in the body portion12. In one embodiment, the central opening is sized to receive thetranslation member 18, and the opening 36 is sized to threadinglyreceive the actuation member 20. In another exemplary embodiment, theopening 36 is sized to receive the actuation member 20 in a ratchetingfashion. In yet another exemplary embodiment, first side portion 28 andsecond side portion 29 each include a recess 38 located towards thesecond end 26 of the body portion 12. The recess 38 is configured anddimensioned to receive an insertion instrument (not shown) that assistsin the insertion of the fusion device 10 into an intervertebral space.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. Turning now toFIGS. 2-6, in an exemplary embodiment, the first endplate 14 has anupper surface 40, a lower surface 42, and a through opening 43. Thethrough opening 43, in an exemplary embodiment, is sized to receive bonegraft or similar bone growth inducing material and further allow thebone graft or similar bone growth inducing material to be packed in thecentral opening in the body portion 12.

In one embodiment, the lower surface 42 includes at least one extension44 extending along at least a portion of the lower surface 42. As bestseen in FIGS. 3 and 4, in an exemplary embodiment, the extension 44 canextend along a substantial portion of the lower surface 42, including,along each side of the endplate 14 and along the front end of theendplate 14. In another exemplary embodiment, the extension 44 includesat least one ramped portion 46, but can include any number of rampedportions, including two spaced ramped portions 46, 48 in the extension44 that extend between each side of the endplate 14, as best seen inFIG. 4. It is contemplated that the slope of the ramped portions 46, 48can be equal or can differ from each other. The effect of varying theslopes of the ramped portions 46, 48 is discussed below.

In an exemplary embodiment, the ramped portions 46, 48 further includegrooved portions 47, 49 that are configured and dimensioned to receiveangled surfaces 58, 60 of the translation member 18 and are oriented inan oblique fashion. In a preferred embodiment, the grooved portions 46,48 are dovetail grooves configured and dimensioned to hold the angledsurfaces 58, 60 of the translation member 18 while allowing the anglessurfaces 58, 60 to slide against the ramped portions 46, 48.

Referring now to FIGS. 3-6, in one embodiment, the upper surface 40 ofthe first endplate 14 is flat and generally planar to allow the uppersurface 40 of the endplate 14 to engage with the adjacent vertebral body2. Alternatively, as shown in FIG. 7, the upper surface 40 can be curvedconvexly or concavely to allow for a greater or lesser degree ofengagement with the adjacent vertebral body 2. It is also contemplatedthat the upper surface 40 can be generally planar but includes agenerally straight ramped surface or a curved ramped surface. The rampedsurface allows for engagement with the adjacent vertebral body 2 in alordotic fashion. Turning back to FIGS. 2-6, in an exemplary embodiment,the upper surface 40 includes texturing 50 to aid in gripping theadjacent vertebral bodies. Although not limited to the following, thetexturing can include teeth, ridges, friction increasing elements,keels, or gripping or purchasing projections.

With reference to FIGS. 2 and 4-6, in an exemplary embodiment, thetranslation member 18 is sized to be received within the central openingof the body portion 12 and includes at least a first expansion portion52. In another embodiment, the translation member 18 includes a firstexpansion portion 52 and a second expansion portion 54, the expansionportions 52, 54 being connected together via a bridge portion 56. It isalso contemplated that there may be more than two expansion portionswhere each of the expansion portions is connected by a bridge portion.The expansion portions 52, 54 each have angled surfaces 58, 60configured and dimensioned to engage the grooved portions 46, 48 of thefirst and second endplates 14, 16. In one embodiment, the translationmember 18 includes an opening 62 in the first expansion portion 52,which is sized to receive a portion of the actuation member 20, as bestseen in FIG. 4. In an exemplary embodiment, the first expansion portion52 includes a central bore 63 that extends from the opening 62 andthrough the first expansion portion 52. In one embodiment, thetranslation member 18 includes a hole 64 in the second expansion portion54, which is sized to receive nose 66, as best seen in FIGS. 5 and 6. Inan exemplary embodiment, the hole 64 includes threading 68 forthreadedly receiving a threaded end 70 of the nose 66, as shown on FIG.6. The nose 66 is received in an opening 72 in the first end 34 of thebody portion 12 to stabilize the translation member 18 in the centralopening of the body portion 12.

In one embodiment, the translation member 18 includes a lockingmechanism 74, which is configured and adapted to engage the actuationmember 20. As illustrated, the locking mechanism 74 may extend from thefirst expansion portion 52. The locking mechanism 74 includes a slot 76configured and adapted to receive extension 87 of the actuation member20. In an exemplary embodiment, the locking mechanism 74 furtherincludes a stop 78 (e.g., a rim, a lip, etc.) that engages the actuationmember 20 when it is disposed in the slot 76.

Referring now to FIGS. 2-6, in an exemplary embodiment, the actuationmember 20 has a first end 80, a second end 82, and threading (notillustrated) extending along at least a portion thereof from the firstend 80 to the second end 82. The threading threadingly engages thethreading that extends along a portion of opening 36 in the body portion12. In another exemplary embodiment, the actuation member 20 includesratchet teeth instead of threading. The ratchet teeth engagecorresponding ratchet teeth in the opening 36 in the body portion 12.The first end 80 includes a recess 84 dimensioned to receive aninstrument (not shown) that is capable of advancing the actuation member20 with respect to the body portion 12 of the fusion device 10. In anembodiment, the actuation member 20 includes a bore 85, as best seen byFIG. 4, that extends from the recess 84 in the first end to the second82. The second end 82 of the actuation member 20 includes an extension86 that is received within the opening 62 in the first expansion portion52. In one embodiment, the extension 88 may include a lip portion 86 anda plurality of slits 88. The plurality of slits 88 are configured toreceive inserts 22. Inserts 22 are provided to limit motion of theactuation member 20. Once the lip portion 86 is placed into the slot 76of the locking mechanism 74, the lip portion 86 will engage the stop 78preventing longitudinal movement of the actuation member 20 with respectto the translation member 18. It is further contemplated that a pinmember 90 can be included to further secure the actuation member 20 inthe translation member 19. In an embodiment, the pin member 90 can bepressed into the central bore 85 of the actuation member 20 and thecentral bore 63 of the translation member, thereby preventing theactuation member 20 from disengaging from the translation member 18.Additionally, in an exemplary embodiment, the fusion device 10 canfurther include a chamfered tip 24 for distraction of adjacentvertebrae.

Turning now to FIGS. 1-6, a method of installing the expandable fusiondevice 10 is now discussed. Prior to insertion of the fusion device 10,the intervertebral space is prepared. In one method of installation, adiskectomy is performed where the intervertebral disc, in its entirety,is removed. Alternatively, only a portion of the intervertebral disc canbe removed. The endplates of the adjacent vertebral bodies 2, 3 are thenscraped to create an exposed end surface for facilitating bone growthacross the invertebral space. The expandable fusion device 10 is thenintroduced into the intervertebral space, with the first end 22 of thebody portion 12 being inserted first into the disc space followed by thesecond end 24. In an exemplary method, the fusion device 10 is in theunexpanded position when introduced into the intervertebral space. Thewedged-shaped first end 22 should assist in distracting the adjacentvertebral bodies 2, 3, if necessary. This allows for the option ofhaving little to no distraction of the intervertebral space prior to theinsertion of the fusion device 10. In another exemplary method, theintervertebral space may be distracted prior to insertion of the fusiondevice 10. The distraction provide some benefits by providing greateraccess to the surgical site making removal of the intervertebral disceasier and making scraping of the endplates of the vertebral bodies 2, 3easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpanded into the expanded position, as best seen in FIGS. 1, 5, and 6,To expand the fusion device 10, an instrument is engaged with recess 84in the actuation member 20. The instrument is used to rotate actuationmember 20. As discussed above, actuation member 20 can be threadinglyengaging body portion 12 and is engaged with translation member 18;thus, as the actuation member 20 is rotated in a first direction, theactuation member 20 and the translation member 18 move with respect tothe body portion 12 toward the first end 22 of the body portion 12. Inanother exemplary embodiment, the actuation member 20 is moved in alinear direction with the ratchet teeth engaging as means forcontrolling the movement of the actuation member 20 and the translationmember 18. As the translation member 18 moves, the angled surfaces 58,60 of the expansion portions 52, 54 push against the ramped portions 46,48 of the endplates 14, 16 pushing endplates 14, 16 outwardly into theexpanded position with the angled surfaces 58, 60 riding along thegrooved portions 47, 48 of the ramped portions 46, 48. This can best beseen in FIGS. 5 and 6. Since the expansion of the fusion device 10 isactuated by a rotational input, the expansion of the fusion device 10 isinfinite. In other words, the endplates 14, 16 can be expanded to aninfinite number of heights dependent on the rotational advancement ofthe actuation member 20. As discussed above, the fusion device 10includes a locking mechanism 22 which assists in retaining the endplates14, 16 at the desired height.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the rampedportions 46, 48 and the angled surfaces 58, 60. As best seen in FIG. 8,the endplates 14, 16 can be expanded in any of the following ways:straight rise expansion, straight rise expansion followed by a toggleinto a lordotic expanded configuration, or a phase off straight riseinto a lordotic expanded configuration.

Turning back to FIGS. 1-6, in the event the fusion device 10 needs to berepositioned or revised after being installed and expanded, the fusiondevice 10 can be contracted back to the unexpanded configuration,repositioned, and expanded again once the desired positioning isachieved. To contract the fusion device 10, the instrument is engagedwith recess 84 in the actuation member 20. The instrument is used torotate actuation member 20. As discussed above, actuation member 20 canbe threadingly engaging body portion 12 and is engaged with translationmember 18; thus, as the actuation member 20 is rotated in a seconddirection, opposite the first direction, the actuation member 20 andtranslation member 18 move with respect to the body portion 12 towardthe second end 26 of the body portion 12. As the translation member 18moves, the angled surfaces 58, 60 of the translation member 18 ridealong the grooved portions 47, 49 pulling the endplates 14, 16 inwardlyinto the unexpanded position.

With reference now to FIG. 9, fusion device 10 is shown with anexemplary embodiment of artificial endplates 100. Artificial endplates100 allows the introduction of lordosis even when the endplates 14 and16 of the fusion device 10 are generally planar. In one embodiment, theartificial endplates 100 have an upper surface 102 and a lower surface104. The upper surfaces 102 of the artificial endplates 100 have atleast one spike 106 to engage the adjacent vertebral bodies. The lowersurfaces 104 have complementary texturing or engagement features ontheir surfaces to engage with the texturing or engagement features onthe upper endplate 14 and the lower endplate 16 of the fusion device 10.In an exemplary embodiment, the upper surface 102 of the artificialendplates 100 have a generally convex profile and the lower surfaces 104have a generally parallel profile to achieve lordosis. In anotherexemplary embodiment, fusion device 10 can be used with only oneartificial endplate 100 to introduce lordosis even when the endplates 14and 16 of the fusion device 10 are generally planar. The artificialendplate 100 can either engage endplate 14 or engage endplate 16 andfunction in the same manner as described above with respect to twoartificial endplates 100.

Referring now to FIGS. 10 and 11, an alternative embodiment of thefusion device 10 is shown. In an exemplary embodiment, the fusion device10 includes a body portion 12, a first endplate 14, a second endplate16, a translation member 18, and an actuation member 20. In theillustrated embodiment, the fusion device further includes a firstramped insert 120 and a second ramped insert 122.

Although the following discussion relates to the first ramped insert120, it should be understood that it also equally applies to the secondramped insert 122 as the second ramped insert 122 is substantiallyidentical to the first ramped insert 120 in embodiments of the presentinvention. Turning now to FIGS. 10-13, in an exemplary embodiment, thefirst ramped insert 120 includes a first ramped portion 124 and a secondramped portion 126, the first and second ramped portions 124, 126 beingconnected by a bridge portion 128. The ramped portions 124, 126 eachhave grooved portions 130, 132 configured and dimensioned to receiveangled surfaces 58, 60 of the translation member. The ramped portions124, 126 can be oriented in an oblique fashion, as illustrated. In apreferred embodiment, the grooved portions 130, 132 are dovetail groovesconfigured and dimensioned to hold the angled surfaces 58, 60 of thetranslation member 18 while allowing the angles surfaces 58, 60 to slideagainst the ramped portions 124, 126.

In an exemplary embodiment, the first ramped insert 120 should beconfigured and dimensioned to be engaged with the first endplate 14. Inan embodiment, the first and second ramped portions 124, 126 includesnap connectors 134, 136 for securing the first ramped insert 120 to thefirst endplate. It should be understood that the snap connectors 134,136 are merely illustrative and that other suitable mechanisms forsecuring the first ramped inserted 120 with the first endplate 14 may beused.

Referring to FIGS. 10-13, in an exemplary embodiment, the translationmember 18 is sized to be received within the central opening of the bodyportion 12 and includes at least a first expansion portion 52. Inanother embodiment, the translation member 18 includes a first expansionportion 52 and a second expansion portion 54, the expansion portions 52,54 being connected together via a bridge portion 56. It is alsocontemplated that there may be more than two expansion portions whereeach of the expansion portions is connected by a bridge portion. Theexpansion portions 52, 54 each have angled surfaces 58, 60 configuredand dimensioned to engage the grooved portions 130, 132 of the first andsecond ramped inserts 120, 122. In one embodiment, the angled surfaces58, 60 include corresponding grooved portions 138, 140, as best seen inFIG. 13, that slidingly engaged the grooved portions 130, 132 of thefirst and second ramped inserts 120, 122.

In one embodiment, the expansion portion 52 includes an opening 62,which is sized to receive a portion of the actuation member 20, and theexpansion portion 62 includes a nose 66, which is received within anopening 72 in the first end 34 of the body portion 12 to stabilize thetranslation member 18 in the central opening of the body portion 12. Inan embodiment, the nose 66 is integral with the expansion portion 62. Inan embodiment (shown on FIGS. 2 and 4-6), the nose 66 is threadinglyengaged with the expansion portion 62. In an embodiment, the translationmember 18 includes a locking mechanism 74 to engage the actuation member20, as illustrated in FIGS. 2-6. However, it should be understood thatother suitable mechanisms may be used to secure the actuation member 20within the translation member 18. For example, the actuation member 20may include an extension 87 having a lip portion 86 (shown on FIGS. 2and 4-6) that engages the expansion portion 62. The extension 87 may,for example, be configured to flex inwardly reducing its diameter whenreceived in the opening 62. Once the lip portion 86 of the extension 87is advanced beyond the end of the opening 62, the extension portion 87will return back to its original diameter and the lip portion 86 willengage the expansion portion 60.

The expandable fusion device 10 of FIGS. 10-13 can be inserted into theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 1-6. After insertion, the expandablefusion device 10 of FIGS. 10-13 can be expanded into the expandedposition, as best seen in FIGS. 10 and 11. To expand the fusion device10, an instrument is engaged with recess 84 in the actuation member 20.The instrument is used to rotate actuation member 20. As discussedabove, actuation member 20 can be threadingly engaging body portion 12and is engaged with translation member 18; thus, as the actuation member20 is rotated in a first direction, the actuation member 20 and thetranslation member 18 move with respect to the body portion 12 towardthe first end 22 of the body portion 12. In another exemplaryembodiment, the actuation member 20 is moved in a linear direction withthe ratchet teeth engaging as means for controlling the movement of theactuation member 20 and the translation member 18. As the translationmember 18 moves, the angled surfaces 58, 60 of the expansion portions52, 54 push against the ramped portions 124, 126 of the first and secondramped inserts 120, 122 while riding along the grooved portions 130,132, thus pushing first and second ramped inserts 120, 122 outwardly.Because the first and second ramped inserts 120, 122 are engaged withthe endplates 14, 16, the endplates 14, 16 are also pushed outwardlyinto the expanded position.

After expansion, the expandable fusion device 10 can be contracted backto the unexpanded configuration. To contract the fusion device 10, theinstrument is engaged with recess 84 in the actuation member 20. Theinstrument is used to rotate actuation member 20. As discussed above,actuation member 20 can be threadingly engaging body portion 12 and isengaged with translation member 18; thus, as the actuation member 20 isrotated in a second direction, opposite the first direction, theactuation member 20 and translation member 18 move with respect to thebody portion 12 toward the second end 26 of the body portion 12. As thetranslation member 18 moves, the angled surfaces 58, 60 of thetranslation member 18 ride along the grooved portions 130, 132 pullingthe first and second ramped inserts 120, 122 and thus, the endplates 14,16 inwardly into the unexpanded position.

Referring now to FIG. 14, an alternative embodiment of the fusion device10 is shown. In an exemplary embodiment, the first endplate 14 and thesecond endplate 16 each include additional geometry to help securelyhold the endplates 14, 16 in place. In an embodiment, the first endplate14 and/or the second endplate 16 include threaded holes 141 throughwhich the fasteners, such as screws 142, may be inserted. In anembodiment, the threaded holes 141 penetrate through the first endplate14 and/or the second endplate 16 in an oblique fashion. It iscontemplated that the screws 142 may inserted through the threaded holes141 and into adjacent vertebral bodies 2, 3, to further secure the firstendplate 14 and the second endplate 16 to the vertebral bodies 2, 3. Insome embodiments, these fasteners may be removed once a more long-terminterface has been established, or alternatively the fasteners mayremain in place indefinitely or until the fusion device 10 needsadjustment and/or replacement.

With reference now FIGS. 15-17, an alternative embodiment of the fusiondevice 10 is shown that expands laterally. Lateral expansion maximizescoverage of the intravertebral disc space for wider load distributionand stability providing a rigid foundation for fusion. In oneembodiment, the fusion device 10 includes body portion 12, firstendplate 144, and second endplate 146.

Although the following discussion relates to the first endplate 144, itshould be understood that it also equally applies to the second endplate146 as the second endplate 146 is substantially identical to the firstendplate 144 in embodiments of the present invention. Turning now toFIGS. 15-17, in an exemplary embodiment, the first endplate 144 has anupper surface 148, a lower surface 150, and an inner surface 151 facingthe body portion 12. It is contemplated that the upper surface 148 willengage adjacent vertebral body 2 (seen on FIG. 1) and the lower surface150 will engage adjacent vertebral body 3 (seen on FIG. 1). In oneembodiment, the upper surface 148 and the lower surface 150 are eachflat and generally planar to allow the upper surface 148 to engage withthe adjacent vertebral body 3. Alternatively, the upper surface 148and/or the lower surface 150 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral bodies 2, 3. It is also contemplated that the upper surface148 and/or the lower surface 150 can be generally planar but includes agenerally straight ramped surface or a curved ramped surface. The rampedsurface allows for engagement with the adjacent vertebral body 2 and/orthe adjacent vertebral body 3 in a lordotic fashion. In an exemplaryembodiment, the upper surface 148 and/or lower surface 150 includestextures 152 to aid in gripping the adjacent vertebral bodies. Althoughnot limited to the following, the texturing can include teeth, ridges,friction increasing elements, keels, or gripping or purchasingprojections.

In one embodiment, the inner surface 151 includes at least one extension154 extending along at least a portion of the inner surface 151. In anexemplary embodiment, the extension 154 can extend along a substantialportion of the inner surface 154, including, along each side of theendplate 144 and along the front end of the endplate 14. While notillustrated, the inner surface may include ramped surfaces and groovedportions in an exemplary embodiment. It is contemplated that the rampedsurfaces and/or grooved portions may be similar to the ramped surfaces46, 48 and grooved portion 47, 49 in extension 44 shown on FIGS. 4-6. Inan embodiment, the extension 154 may include slots 156 oriented in anoblique fashion through which pins 158 may be inserted.

While not illustrated, the fusion device 10 further includes features toeffectuate the lateral expansion of the first and second endplates 144,146. In one embodiment, the fusion device 10 using a rampingsystem—similar to the system illustrated in FIGS. 2 and 4-6—forexpanding the first and second endplates 144, 146. In an exemplaryembodiment, the fusion device 10 further includes a translation memberand actuation member, such as translation member 18 and actuation member20 shown on FIGS. 2 and 4-6. It is contemplated that the translationmember may include angled surfaces that push against ramped surfaces inthe extension 154, expanding the first and second endplates 144, 146outwardly and away from the body portion 12. In an embodiment, pins 156disposed through the slots 154 may be retained in the translationmember. In an alternative embodiment, dovetailing may be used forengagement of the angled surfaces and ramped surfaces. It should beunderstood that the translation member and actuation member in thisembodiment may be similar to the translation member 18 and actuationmember 20 described above with respect FIGS. 1-6. In another embodiment,the fusion device 10 further includes first and second ramped insertsthat are secured within the first and second endplates 144, 146. Thefirst and second ramped inserts may be similar to the first and secondramped inserts 120, 122 described above with respect to FIGS. 10-13. Itis contemplated that angled surfaces in the translation member may pushagainst ramped surfaces in the ramped inserts pushing the ramped insertsoutwardly. Because of their engagement with the first and secondendplates 144, 146, the first and second endplates 144, 146 may thus beexpanded outwardly. In this manner, the first and second endplates 144,146 may be laterally expanded away from the body portion 12. It shouldbe understood that other suitable techniques may also be used toeffectuate this lateral expansion.

With reference to FIG. 18, an exploded perspective view of anotherembodiment of fusion device 10 is shown. In an exemplary embodiment, thefusion device 10 includes a body portion 12, a first endplate 200, asecond endplate 202, a third endplate 204, a fourth endplate 206, and atranslation member 18. In this embodiment, the fusion device 10 isconfigured to expand both vertically and laterally.

In an exemplary embodiment, the body portion 12 has a first end 24, asecond end 26, a first side portion 28 connecting the first end 24 andthe second end 26, and a second side portion 29 on the opposing side ofthe body portion 12 connecting the first end 24 and the second end 26.The body portion 12 further includes a top side portion 208 connectingthe first end 24 and the second end 26, and a bottom side portion 210 onthe opposing side of the body portion 12 connecting the first end 24 andthe second end 26. The body portion 12 further includes first gap 212between the top side portion 208 and the first side portion 28, which issized to receive at least a portion of the first endplate 200. The bodyportion 12 further includes second gap 214 between the top side portion208 and the second side portion 29, which is sized to receive at least aportion of the second endplate 202. The body portion 12 further includesthird gap 216 between the bottom side portion 210 and the first sideportion 28, which is sized to receive at least a portion of the thirdendplate 204. The body portion 12 further includes fourth gap 218between the bottom side portion 210 and the second side portion 29,which is sized to receive at least a portion of the fourth endplate 206.

The first end 24 of the body portion 12, in an exemplary embodiment,includes an opening 220. The opening 220 extends from the first end 24of the body portion 12 into a central opening 222. In one embodiment,the central opening 222 is sized to receive the translation member 18.The second end 26 of the body portion 12, in an exemplary embodiment,includes an opening 36, which extends from the second end 26 of the bodyportion 12 into the central opening 222.

Although the following discussion relates to the first endplate 200, itshould be understood that it also equally applies to the second endplate202, the third endplate 204, and the fourth endplate 206, as theseendplates 202, 204, 206 are substantially identical to the firstendplate 200 in embodiments of the present invention. Turning now toFIGS. 18-20, in an exemplary embodiment, the first endplate 14 has afirst end 224 and a second end 226. The first endplate further includesan upper surface 40 connecting the first end 224 and the second end 226and a lower surface 42 on an opposing side of the endplate 200connecting the first end 224 and the second end 226. While notillustrated, the first endplate 14 may include a through opening sizedto receive bone graft or similar bone growth inducing material andfurther allow the bone graft or similar bone growth inducing material tobe packed in the central opening 222 in the body portion 12.

In one embodiment, the lower surface 42 includes at least one firstretaining socket 228 on the lower surface 42. In an exemplaryembodiment, the lower surface 42 includes a first retaining socket 228at the interior corner of the intersection of the first end 224 and thelower surface 42, and a second retaining socket 230 at the interiorcorner of the intersection of the first end 224 and the lower surface42.

Referring now to FIGS. 18-20, in one embodiment, the upper surface 40 ofthe first endplate 200 is curved convexly. Alternatively, the uppersurface 40 is flat or curved concavely to allow for a greater or lesserdegree of engagement with the adjacent vertebral body 2. It is alsocontemplated that the upper surface 40 can be generally planar butincludes a generally straight ramped surface or a curved ramped surface.The ramped surface allows for engagement with the adjacent vertebralbody 2 in a lordotic fashion. In an exemplary embodiment, the uppersurface 40 includes texturing 50 to aid in gripping the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections.

With reference to FIG. 18, in an exemplary embodiment, the translationmember 18 is sized to be received within the central opening 222 of thebody portion 12. The translation member 18 should be sized to allowlongitudinal translation within the central opening 222. In anembodiment, the translation member 18 includes at least a firstexpansion portion 52. In another embodiment, the translation member 18includes a first expansion portion 52 and a second expansion portion 54,the expansion portions 52, 54 being connected together via a bridgeportion 56. It is also contemplated that there may be more than twoexpansion portions where each of the expansion portions is connected bya bridge portion. The expansion portions 52, 54 each have angledsurfaces 58, 60. In an embodiment, the angles surfaces 58, 60 eachcomprise first end 229 and second end 231 with second end 231 beingwider than the first end 229. In an exemplary embodiment, the expansionportions 52, 54 include grooved portions 232, 234 on the edges of atleast two sides (e.g., the lateral sides) of the angled surfaces 58, 60.The grooved portions 232, 234 are configured and dimensioned to engagethe first and second retaining sockets 228, 230 on the endplates 200,202, 204, 206. In an exemplary embodiment, the grooved portions 232, 234retain the first and second retaining sockets 228, 230 in slidingengagement.

In one embodiment, the translation member 18 includes a first end 236and a second end 238. The first end 236 of the translation memberincludes an extension 240 sized to be received within the opening 220 inthe first end 24 of the body portion 12. While not illustrated, thesecond end 238 also can include a similar extension sized to be receivedwithin opening 32 in the second end 26 of the body portion 12.

The expandable fusion device 10 of FIGS. 18-20 can be inserted into theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 1-6. After insertion, the expandablefusion device 10 of FIGS. 18-20 can be expanded into the expandedposition. As previously mentioned, the fusion device 10 shown on FIGS.18-20 expands both vertically and laterally. To expand the fusion device10, the translation member 18 can be moved with respect to the bodyportion 12 toward the first end 24 of the body portion. An instrumentcan be used, in an exemplary embodiment. As the translation member 18moves, the first retaining socket 228 and the second retaining socket230 ride along the grooved portions 232, 234 of the expansion portions52, 54 pushing the endplates 200, 202, 204, 206 outwardly in thedirection indicated by arrows 242. In an embodiment, the endplates 200,202, 204, 206 move outwardly in an oblique fashion to expand the fusiondevice 10 both vertically and laterally. The expanded configuration ofthe expansion device 10 is best seen in FIG. 20.

After expansion, the expandable fusion device 10 can be contracted backto the unexpanded configuration. The unexpanded configuration of thefusion device 10 is best seen in FIG. 20. To contract the fusion device10, the translation member 18 is moved with respect to the body portion12 toward the second end 26 of the body portion 12. As the translationmember 18 moves, the first retaining socket 228 and the second retainingsocket 230 ride along the grooved portions 232, 234 of the expansionportions 52, 54 pulling the endplates 200, 202, 204, 206 inwardly in adirection opposite that indicated by arrows 242. In an embodiment, theendplates 200, 202, 204, 206 move inwardly in an oblique fashion tocontract the fusion device 10 both vertically and laterally. Theunexpanded configuration of the expansion device 10 is best seen in FIG.19.

With reference to FIGS. 21-22, another embodiment of expandable fusiondevice 10 is shown. In an exemplary embodiment, the fusion device 10includes a body portion 12, a vertically expanding plate 300, and a gear302. In this embodiment, a portion of the fusion device 10 is configuredto expand vertically in at least one direction. In an exemplaryembodiment, the vertically expanding plate 300 is configured to expandoutwardly from the body portion 12. It is contemplated that anexpandable fusion device 10 may be used to correct spinal curvature dueto, for example, scoliosis, lordosis, and the like.

In an exemplary embodiment, the body portion 12 has a first end 24, asecond end 26, a first side portion 28 connecting the first end 24 andthe second end 26, and a second side portion 29 on the opposing side ofthe body portion 12 connecting the first end 24 and the second end 26.The first end 24 of the body portion 12, in an exemplary embodiment,includes at least one angled surface 34, but can include multiple angledsurfaces. The angled surface 34 can serve to distract the adjacentvertebral bodies when the fusion device 10 is inserted into anintervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 10 is inserted into an intervertebralspace. In yet another preferred embodiment, first side portion 28 andsecond side portion 29 each include a recess 38 located towards thesecond end 26 of the body portion 12. The recess 38 is configured anddimensioned to receive an insertion instrument 304 that assists in theinsertion of the fusion device 10 into an intervertebral space.

In an exemplary embodiment, the body portion 12 includes an upperengagement surface 306 extending from the first end 24 towards thesecond end 26, and a lower engagement surface 308 extending between thefirst end 24 and the second end 26. In an embodiment, the upperengagement surface 306 has a through opening 310. Although notillustrated, the lower engagement surface 308 may have a through openingthat is similar to through opening 310. The through opening 310, in anexemplary embodiment, is sized to receive bone graft or similar bonegrowth inducing material and further allow the bone graft or similarbone growth inducing material to be packed in the central opening in thebody portion 12. In an embodiment, at least a portion of the bodyportion 12 is removed to form a landing 312 in the body portion 12. Inan exemplary embodiment, a portion of the upper engagement surface 306and the second end 26 are removed to form the landing 312 having anupper surface 314. While not illustrated, a portion of the lowerengagement surface 308 and the second end 26 may be cut away, in analternative embodiment, to form the landing 312.

In one embodiment, the upper engagement surface 306 and the lowerengagement surface 308 are flat and generally planar to allow engagementsurfaces 306 to engage with the adjacent vertebral body 2 and the lowerengagement surface 308 to engage with the adjacent vertebral body 3.Alternatively, the upper engagement surface 306 and/or the lowerengagement surface 308 can be curved convexly or concavely to allow fora greater or lesser degree of engagement with the adjacent vertebralbodies 2, 3. In an exemplary embodiment, the upper engagement surface306 and/or the lower engagement surface includes texturing 312 to aid ingripping the adjacent vertebral bodies. Although not limited to thefollowing, the texturing can include teeth, ridges, friction increasingelements, keels, or gripping or purchasing projections.

In an exemplary embodiment, vertically expanding plate 300 is coupled toan end of threaded bolt 318, which is coupled to the gear 302. In oneembodiment, the threaded bolt 318 is in threaded engagement with thegear 302. In an alternative embodiment, a bolt having ratchet teeth maybe used instead of threaded bolt 318. In an embodiment, the gear 302 iscoupled to the landing 312. In one embodiment, the gear 302 is rotatablycoupled to the landing 312.

The vertically expanding plate 300 includes a throughbore 319 and anupper surface 320. In one embodiment, the vertically expanding plate 300is generally circular in shape. Other suitable configurations of theexpanding plate 300 may also be suitable. In an embodiment, thevertically expanding plate may be generally rectangular in shape withrounded corners, as best seen in FIG. 23. In one embodiment, thevertically expanding plate 300 is flat and generally planar to allowupper surface 320 to engage with the adjacent vertebral body 2.Alternatively, the upper surface 320 can be curved convexly or concavelyto allow for a greater or lesser degree of engagement with the adjacentvertebral bodies. In an exemplary embodiment, the upper surface 320includes texturing 322 to aid in gripping the adjacent vertebral bodies.Although not limited to the following, the texturing can include teeth,ridges, friction increasing elements, keels, or gripping or purchasingprojections.

With reference to FIG. 23, an alternative embodiment of the expandablefusion device 10 of FIGS. 21-22 is shown. In this embodiment, the gear302 is enclosed within the body portion 12 towards the second end 26 ofthe body portion 12 with the vertically expanding plate 300 disposed ator above the upper engagement surface 306 of the body portion 12. In anembodiment, the vertically expanding plate 300 is positioned towards thesecond end 26 of the body portion 12. While not illustrated, thethreaded bolt 318 extends through the upper engagement surface 306 andcouples the vertically expanding plate 300 and the gear 302. An actuatorscrew 324 extends through the first end 24 of the body portion 12 toengage the gear 302.

The expandable fusion device 10 of FIGS. 21-23 can be inserted in theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 1-6. FIG. 24 illustrates the expandablefusion device 10 of FIG. 23 between adjacent vertebral bodies 3, 4 in anunexpanded position. After insertion, the expandable fusion device 10 ofFIGS. 21-23 can be expanded into the expanded position. As previouslymentioned, a portion of the fusion device shown on FIGS. 21-23 expandsvertically in at least one direction. To partially expand the fusiondevice 10, the gear 302 can be rotated in a first direction. Aninstrument 326 having a gear 328 disposed on a distal end 330 of theinstrument may be used to rotate the gear 302, as best seen on FIG. 22.In another embodiment, an instrument (not illustrated) may be used torotate actuation member 324 in a first direction. As discussed above,the actuation member 324 is engaged with gear 302; thus, as theactuation member 324 is rotated in first direction, the gear 302 rotatedin a first direction. The embodiment with the actuation member 324 isbest seen in FIG. 23. As the gear 302 rotates, the threaded bolt 318extends outward from the gear 302, thus extending the laterallyexpanding plate 300 outward from the body portion 12. FIG. 25illustrates the expandable fusion device 10 of FIG. 23 in an expandedposition.

After expansion, the expandable fusion device 10 can be contracted backto the unexpanded position. The unexpanded position of the fusion device10 is best seen in FIG. 24. To contract the fusion device 10, the gear302 is rotated in a second direction that is opposite the firstdirection. The instrument 326 with the gear 328 may be used to rotatethe gear 302. Alternatively, an instrument may be used to rotate theactuation member 324 to turn the gear 302 in the second direction. Asthe gear 302 rotates in the second direction, the threaded bolt 318retracts pulling the laterally expanding plate 300 inward into theunexpanded position.

Although the preceding discussion only discussed having a single fusiondevice 10 in the intervertebral space, it is contemplated that more thanone fusion device 10 can be inserted in the intervertebral space. It isfurther contemplated that each fusion device 10 does not have to befinally installed in the fully expanded state. Rather, depending on thelocation of the fusion device 10 in the intervertebral disc space, theheight of the fusion device 10 may vary from unexpanded to fullyexpanded.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. An intervertebral implant comprising: a bodyportion having a central opening; a first endplate comprising an upperside, a lower side, a first ramped portion and a second ramped portion,the first and second ramped portions extending from the lower side intothe central opening; a second endplate comprising an upper side, a lowerside, a third ramped portion, and a fourth ramped portion, the third andfourth ramped portions extending from the lower side into the centralopening; and a translation member received within the central opening,the translation member comprising a first angled surface, a secondangled surface, the first angled surface engages the first rampedportion, and the second angled surface engages the second rampedportion; wherein movement of the translation member in a first directioncauses the first and second endplates to move in a direction away fromthe body portion and the movement of the translation member in a seconddirection causes the first and second endplates to move in a directiontowards the body portion, and wherein the first and second angledsurface are at a first distance from each other when the first endplateis in an unexpanded position and at a second distance at an expandedposition, wherein the first and second distances are equal.
 2. Theintervertebral implant of claim 1, further comprising an actuationmember coupled to the translation member, the actuation member having afirst end and a second end, the first end comprising an extension thatis received within the translation member.
 3. The intervertebral implantof claim 2, wherein the rotational movement of the actuation memberresults in the generally linear movement of the translation member. 4.The intervertebral implant of claim 2, wherein the extension of theactuation member comprises a lip portion, wherein the lip portion isreceived in a locking mechanism that extends from the expansion portionof the translation member, the locking mechanism comprising a slotconfigured to receive the lip portion of the extension and a stopconfigured to engage the lip portion when the lip portion is in theslot.
 5. The intervertebral implant of claim 2, further comprising a pinmember for securing the actuation member in the translation member, thepin member disposed through a central bore of the actuation member andthrough a central bore of the actuation member.
 6. The intervertebralimplant of claim 1, wherein the first endplate comprises an openingextending from the upper surface through the lower surface, the openingbeing in fluid communication with the central opening, and wherein theupper surface of the first endplate comprises at least one texturingselected from the group consisting of teeth, ridges, friction increasingelements, keels, gripping projections, and purchasing projections. 7.The intervertebral implant of claim 1, wherein the first endplatecomprise a threaded hole, the threaded hole penetrating through theupper surface of the first endplate, the threaded hole extending throughthe first endplate in an oblique fashion.
 8. The intervertebral implantof claim 1, wherein the translation member comprises a second expansionportion.
 9. The intervertebral implant of claim 1, wherein first angledsurface of the expansion portion engages the first endplate in a slottedfashion.
 10. The intervertebral implant of claim 1, wherein portions ofthe first and second endplates extend in a generally oblique manner. 11.The intervertebral implant of claim 1, wherein first and second sides ofthe body portion each comprise a recessed portion configured anddimensioned for receiving an insertion instrument.
 12. Theintervertebral implant of claim 1, wherein the first end of the bodyportion includes at least one angled surface.
 13. The intervertebralimplant of claim 1, the intervertebral implant further comprising: firstand second artificial endplates, the artificial endplates each have anupper surface and a lower surface, the upper surfaces of the artificialendplates comprise a spike to engage the adjacent vertebral bodies andthe lower surfaces of the artificial endplates comprise complementarytexturing or engagement features to engage with texturing or engagementfeatures on the first and second endplates, wherein the upper surfacesof the artificial endplates have a generally convex profile and thelower surfaces have a generally parallel profile to achieve lordosis.14. A method of installing an intervertebral implant, the methodcomprising: positioning the intervertebral implant between adjacentvertebrae, the intervertebral implant comprising a body portion with afirst end and a second end, a first endplate having firt and secondramped portions, an actuation member, and a translation member, thetranslation member comprising a first angled surface and a second angledsurface; rotating the actuation member of the intervertebral implant ina first direction, the rotation of the actuation member moves thetranslation member in a first direction thereby causing the first angledsurface to push against the first ramped surface of the first endplateand the second angled surface to push against the second ramped surfaceof the first endplate moving the first endplate in a direction away fromthe body portion into an expanded position, wherein the first and secondangled surface are at a distance from each other when the first endplateis in an unexpanded position and at a second distance in an expandedposition, wherein the first and second distances are equal.
 15. Anintervertebral implant comprising: a body portion having a centralopening; a first endplate comprising a first ramped portion and a secondramped portion, the first and second ramped portions extending downwardfrom the first endplate into the central opening; a second endplatecomprising a third ramped portion, and a fourth ramped portion, thethird and fourth ramped portions extending upward from the secondendplate into the central opening; and a translation member receivedwithin the central opening, the translation member comprising a firstangled surface, a second angled surface, the first angled surfaceengages the first ramped portion, and the second angled surface engagesthe second ramped portion; wherein movement of the translation member ina first direction causes the first and second endplates to move in adirection away from the body portion and the movement of the translationmember in a second direction causes the first and second endplates tomove in a direction towards the body portion, and wherein the first andsecond angled surface are at a first distance from each other when thefirst endplate is in an unexpanded position and at a second distance atan expanded position, wherein the first and second distances are equal.